(8)Experimental study of entrainment of phases in copper solvent extraction

摘要

Solvent extraction (SX) is a technology that has been widely used inextractive metallurgy. The SX has been positioned as a key technique forpurification and concentration of solutions containing copper ions. Thecopper solvent extraction on an industrial scale employs a mixer-settlerreactor, in which in a first instance two immiscible liquid phases are mixedby mechanical stirring, and subsequently they are recovered separately.This operation has a number of difficulties as crud formation, degradationof organic reagent and entrainment of phases. This last problem involvesthe transportation of organic micro-droplets in aqueous phase (or viceversa), which does not coalesce with the respective phase. Thisphenomenon is common and causes problems such as contamination ofthe rich electrolyte (reducing the quality of electrodeposited cathode), andheap leach (to be irrigated with solutions containing organic droplets), etc.In this paper the results to evaluate the entrainment of organic phases inthe aqueous at laboratory level are presented. The conditions tested are:agitation speed, agitation time and extractant concentration. Theexperiments were conducted in a reactor equipped with four baffles whichhad a capacity of 1 L and an internal diameter of 10 cm. The organic phaseused consists of a commercial extractant and diluent (LIX 984N andShellsol-2046AR), the aqueous phase consists of a copper sulfate solution atpH 2. To measure the entrainment of phases UV-VIS spectrophotometrywas used. The results indicated levels of entrainment of phases between160 ppm and 312 ppm. An analysis of the variables studied shows that thephenomenon is mainly influenced by the size of droplets and the speed ofthe phase separation.